在SelectList集合中设置所选项目 [英] Set Selected Item in SelectList Collection

问题描述

我有一个具有以下属性的类.它从现有列表中构造一个 SelectList 对象，然后设置所选项目.

I have a class with the following property. It constructs a SelectList object from an existing list, and then sets the selected item.

public SelectList ProviderTypeList
{
    get
    {
        SelectList list = new SelectList([...my collection...], "Value", "Key");
        SelectListItem item = list.FirstOrDefault(sli => sli.Text == SelectedProviderType);
        if (item != null)
           item.Selected = true;
       return list;
    }
}

但是，此代码完成后， item.Selected 为true.但是 SelectList 集合中的对应项目仍然为空.

However, when this code is finished, item.Selected is true. But the corresponding item in the SelectList collection is still null.

我似乎找不到一种方法来更新集合中的对象，因此该设置将用于结果HTML中.

I can't seem to find a way to update the object in the collection, so that the setting will be used in the resulting HTML.

我正在使用 @ Html.DropDownListFor 呈现HTML.但是我可以看到，执行此代码后，集合中的对象没有被修改.

I'm using @Html.DropDownListFor to render the HTML. But I can see that the object within the collection was not modified as soon as this code has executed.

任何人都可以看到我所缺少的吗?

Can anyone see what I'm missing?

推荐答案

SelectList

SelectList list = new SelectList([...my collection...], "Value", "Key", SelectedID);

检查定义

public SelectList(IEnumerable items, string dataValueField, string dataTextField, 
object selectedValue);

设置所选值，并且与 dataValueField

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